Pete Fornatale, a disc jockey who helped usher in a musical alternative to Top 40 AM radio in New York in the late 1960s and early 1970s, presenting progressive rock and long album tracks that AM stations wouldn’t touch and helping to give WNEW a major presence on the still-young FM dial, died on Thursday in Manhattan. He was 66.


The cause was complications of a stroke, his son Mark said.


FM radio had been around for a while but did not come of age until the 1960s, when, amid the whirlwind of a growing counterculture, the federal government mandated that FM stations carry different programming from that of their sister AM bands. Enterprising D.J.’s grasped the chance to play longer, fresher, rarer music and give voice to the roiling political and social issues of the day.


Mr. Fornatale was at the forefront of the FM revolution, along with WNEW-FM colleagues like Scott Muni, Rosko, Vin Scelsa, Dennis Elsas, Jonathan Schwartz and Alison Steele (who called herself “the Nightbird”). They played long versions of songs, and sometimes entire albums, and talked to their audiences in a conversational tone very different from the hard-sell approach of their AM counterparts.


WNEW-FM may have been the most influential experimenter. When the station dropped rock music for talk radio in 1999, Billboard called it “a legend, affecting and inspiring people throughout the industry.”


Mr. Fornatale (pronounced forn-a-TELL) had actually beaten WNEW to the punch. As a sophomore at Fordham University in 1964, he persuaded the school’s Jesuit leaders to let him do a free-form rock show on what was officially an educational station. He continued that show for a few years after he graduated, and for a while could be heard on both WFUV and WNEW.


WOR-FM became the first commercial station in New York to adopt the format, in 1966, but abandoned it after about a year. WNEW, with the slogan “Where Rock Lives,” adopted it in 1967.


Mr. Fornatale came on board in 1969 and quickly moved to the center of New York’s music scene. He gave early exposure to country-rock bands like Buffalo Springfield and Poco. He did one of the first American interviews with Elton John, and got a rousing ovation when he brought a rented surfboard to Carnegie Hall for a Beach Boys show. He introduced Curtis Mayfield to Bob Dylan at a Muhammad Ali fight.


In 1982 he started “Mixed Bag,” a program that emphasized singer-songwriters, on Sunday mornings. His regular guests included Suzanne Vega, who introduced herself to him by sending a fan letter.


One of Mr. Fornatale’s signatures was playing songs that followed a theme. It might be colors, with a playlist including the Beatles’ “Yellow Submarine” and Joni Mitchell’s “Blue.” Or it might be great inventions, as when he celebrated the 214th anniversary of the United States Patent Office. Or the theme might simply be radio.


Peter Fornatale was born in the Bronx on Aug. 23, 1945, and graduated from Fordham Preparatory School, on the campus of Fordham University. His introduction to rock ’n’ roll came in 1956 when his father summoned him to the television to see “this crazy guy” — Elvis Presley. The first record he bought was Presley’s “Hound Dog.”


Mr. Fornatale graduated from Fordham with a degree in communications in 1967 and taught English at a Roman Catholic high school before joining WNEW. His voice drew praise for its mellow, almost professorial tone, although some listeners may have chosen to describe it as nasal.


By the early 1980s, stations specializing in what had been known as free-form radio were bringing in business consultants who urged less variety in records and more control over the disc jockeys. Mr. Fornatale later complained that he and his colleagues had been demoted from chefs into waiters, “and fast-food waiters at that,” as he told The Record of Bergen County, N.J., in 1999.


He left WNEW in 1989 to follow the station’s program director to WXRK-FM (K-Rock), which followed a more conventional approach to pop music. Mr. Fornatale’s show came on after Howard Stern’s. Mr. Stern, whose shock-jock format was becoming radio’s new wave, called Mr. Fornatale the “anti-Stern.”


In 1997 Mr. Fornatale returned to WNEW-FM, which had decided to go back to album-oriented rock after a succession of owners and formats. But within a year the station had changed formats again, to talk. In 2001, Mr. Fornatale returned to where he had started: WFUV. “I love the idea I’ve come full circle,” he said.


Mr. Fornatale wrote several books, including one on the making of Simon and Garfunkel’s 1968 album “Bookends,” and one on the Woodstock music festival. He was also the main writer for a series of 600 trading cards on the life of Elvis Presley.


He had lived for six years in Rockaway, Queens, and the previous four decades in Port Washington, N.Y.


Mr. Fornatale’s marriage to Susan Kay Flynn ended in divorce several years ago. He is survived by his sons, Peter, Mark and Steven, and his brother, Robert.


His WFUV show, which like his earlier WNEW singer-songwriter show was called “Mixed Bag,” ran from 4 to 8 p.m. on Saturdays.


“If you give me the right idea for a program,” Mr. Fornatale said in 2004, “I can give back to you a three-hour journey where, if you tune in at any time, you’re likely to hear something that will entertain you. But if you take the ride with me, when we get to the end, you’ll say, ‘Wow, what a long, strange trip it’s been.’ ”